What does the Autumnal Equinox Day API do?

Return autumn equinox date, UTC time, seasonal markers, and optional countdown data. Use it to add this utility without rebuilding formulas, validation, examples, and documentation.

How much does one call to Autumnal Equinox Day cost?

1 credit per successful call. Failed calls (validation errors, 5xx) don't bill.

What parameters does the Autumnal Equinox Day API require?

Required fields: (none). Full schema at /v1/openapi.json.

Is the Autumnal Equinox Day API deterministic?

Yes — same input, same output, forever. Tool version 2026-04-22; output shape is stable within a major version.

Can an AI agent call the Autumnal Equinox Day API?

Yes. Connect to https://api.miniwebtool.com/v1/mcp over the Model Context Protocol. The agent discovers `autumnal-equinox-day` with its JSON Schema automatically, so the model can plan while MiniWebtool handles the exact tool result.

What format does the API return?

JSON with a stable envelope: `{request_id, tool, tool_version, credits_used, result}`. Errors are RFC 7807 `application/problem+json`.

Autumnal Equinox Day API

Field	Type	Req.
`year`	`int`	—
`hemisphere` north \| south	`str`	—
`as_of_utc` Optional ISO datetime for countdown	`str \| None`	—

Field

Type

Req.

year

int

—

hemisphere

north | south

str

—

as_of_utc

Optional ISO datetime for countdown

str | None

—

import requests resp = requests.post( 'https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run', headers={'Authorization': 'Bearer mwt_live_YOUR_KEY'}, json={}, ) resp.raise_for_status() data = resp.json() print(data)

<?php $ch = curl_init('https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run'); curl_setopt_array($ch, [ CURLOPT_POST => true, CURLOPT_RETURNTRANSFER => true, CURLOPT_HTTPHEADER => [ 'Authorization: Bearer mwt_live_YOUR_KEY', 'Content-Type: application/json', ], CURLOPT_POSTFIELDS => json_encode([ ]), ]); $resp = curl_exec($ch); curl_close($ch); print_r(json_decode($resp, true));

require 'net/http' require 'json' require 'uri' uri = URI('https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run') http = Net::HTTP.new(uri.host, uri.port) http.use_ssl = (uri.scheme == 'https') req = Net::HTTP::Post.new(uri) req['Authorization'] = 'Bearer mwt_live_YOUR_KEY' req['Content-Type'] = 'application/json' req.body = { }.to_json resp = http.request(req) puts JSON.parse(resp.body).inspect

package main import ( "bytes" "encoding/json" "fmt" "io" "net/http" ) func main() { body, _ := json.Marshal(map[string]interface{}{ , }) req, _ := http.NewRequest("POST", "https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run", bytes.NewReader(body)) req.Header.Set("Authorization", "Bearer mwt_live_YOUR_KEY") req.Header.Set("Content-Type", "application/json") resp, err := http.DefaultClient.Do(req) if err != nil { panic(err) } defer resp.Body.Close() out, _ := io.ReadAll(resp.Body) fmt.Println(string(out)) }

import java.net.URI; import java.net.http.*; var client = HttpClient.newHttpClient(); var req = HttpRequest.newBuilder() .uri(URI.create("https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run")) .header("Authorization", "Bearer mwt_live_YOUR_KEY") .header("Content-Type", "application/json") .POST(HttpRequest.BodyPublishers.ofString("{}")) .build(); var resp = client.send(req, HttpResponse.BodyHandlers.ofString()); System.out.println(resp.body());

Integrate the MiniWebtool Autumnal Equinox Day API into this project. ## Your task 1. Read the reference below. 2. Ask me where this belongs in the codebase if it is not obvious. 3. Write the integration in the language and style of the surrounding code: a small typed client function, errors handled, key read from the environment (never hard-coded, never committed). 4. Verify with `/dry-run` first, then exactly one live call. 5. Show me the diff and the live result. ## Credit budget — follow these exactly This API is metered. A live call costs 1 credit; the free tier includes 1,000 credits per month. Burning them during integration is the single most common way to waste this key. 1. **Do all wiring against `/dry-run`, which costs 0 credits.** It validates the payload for real and returns a sample result with the exact response shape. Iterate there until your request builds and your parsing works. 2. **Make at most ONE live `/run` call** — a single end-to-end confirmation once dry-run passes. Print the result, then stop. 3. **Never call the API from unit tests, examples, or a retry loop.** Assert against the sample response captured from `/dry-run` instead. 4. **On 4xx, fix the payload — do not retry.** The error body is RFC 7807 `application/problem+json` and says exactly what is wrong. 5. **On 429, honour `Retry-After`** and back off; do not tighten the loop. 6. **Read `X-MWT-Credits-Remaining`** on every response. If it drops below 50, stop making live calls and tell me. 7. If the integration needs repeated calls at runtime, **cache by input** — this tool is deterministic, so the same input always returns the same output. ## The API **Autumnal Equinox Day** — Return autumn equinox date, UTC time, seasonal markers, and optional countdown data. - Live endpoint: `POST https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run` — costs 1 credit - Dry run: `POST https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/dry-run` — costs 0 credits, same auth and validation - Auth: `Authorization: Bearer <MINIWEBTOOL_API_KEY>` - Content type: `application/json` - Tool version: `2026-04-22` (output shape is stable within a major version) - Full machine-readable spec: `https://api.miniwebtool.com/v1/openapi.json` ### Request body | field | type | required | notes | |---|---|---|---| | `year` | int | no | (default `2026`) | | `hemisphere` | str | no | one of: north, south — north \| south (default `north`) | | `as_of_utc` | str | None | no | Optional ISO datetime for countdown | Example request body: ```json {} ``` ### Response envelope ```json { "request_id": "req_01H…", "tool": "autumnal-equinox-day", "tool_version": "2026-04-22", "credits_used": 1, "result": { "year": 2026, "hemisphere": "north", "event_label": "September Equinox", "season_name": "Autumn", "date": "2026-09-23", "time_utc": "00:05", "datetime_utc": "2026-09-23T00:05:00Z", "day_of_week": "Wednesday", "season_duration": { "days": 89, "hours": 20, "minutes": 45, "total_days": 89.8646 }, "season_markers": { "march_equinox": "2026-03-20T14:46:00Z", "june_solstice": "2026-06-21T08:24:00Z", "september_equinox": "2026-09-23T00:05:00Z", "december_solstice": "2026-12-21T20:50:00Z" } } } ``` `result` holds the tool output. Errors come back as `application/problem+json` with `type`, `title`, `status`, and `detail`. ### Getting a key If `MINIWEBTOOL_API_KEY` is not already in the environment, stop and ask me for one — do not sign up, scrape, or guess a key. Free keys: https://api.miniwebtool.com/dashboard/

--- description: MiniWebtool Autumnal Equinox Day API — usage and credit budget globs: alwaysApply: false --- # MiniWebtool Autumnal Equinox Day API ## The API **Autumnal Equinox Day** — Return autumn equinox date, UTC time, seasonal markers, and optional countdown data. - Live endpoint: `POST https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run` — costs 1 credit - Dry run: `POST https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/dry-run` — costs 0 credits, same auth and validation - Auth: `Authorization: Bearer <MINIWEBTOOL_API_KEY>` - Content type: `application/json` - Tool version: `2026-04-22` (output shape is stable within a major version) - Full machine-readable spec: `https://api.miniwebtool.com/v1/openapi.json` ### Request body | field | type | required | notes | |---|---|---|---| | `year` | int | no | (default `2026`) | | `hemisphere` | str | no | one of: north, south — north \| south (default `north`) | | `as_of_utc` | str | None | no | Optional ISO datetime for countdown | Example request body: ```json {} ``` ### Response envelope ```json { "request_id": "req_01H…", "tool": "autumnal-equinox-day", "tool_version": "2026-04-22", "credits_used": 1, "result": { "year": 2026, "hemisphere": "north", "event_label": "September Equinox", "season_name": "Autumn", "date": "2026-09-23", "time_utc": "00:05", "datetime_utc": "2026-09-23T00:05:00Z", "day_of_week": "Wednesday", "season_duration": { "days": 89, "hours": 20, "minutes": 45, "total_days": 89.8646 }, "season_markers": { "march_equinox": "2026-03-20T14:46:00Z", "june_solstice": "2026-06-21T08:24:00Z", "september_equinox": "2026-09-23T00:05:00Z", "december_solstice": "2026-12-21T20:50:00Z" } } } ``` `result` holds the tool output. Errors come back as `application/problem+json` with `type`, `title`, `status`, and `detail`. ### Getting a key If `MINIWEBTOOL_API_KEY` is not already in the environment, stop and ask me for one — do not sign up, scrape, or guess a key. Free keys: https://api.miniwebtool.com/dashboard/ ## Credit budget — follow these exactly This API is metered. A live call costs 1 credit; the free tier includes 1,000 credits per month. Burning them during integration is the single most common way to waste this key. 1. **Do all wiring against `/dry-run`, which costs 0 credits.** It validates the payload for real and returns a sample result with the exact response shape. Iterate there until your request builds and your parsing works. 2. **Make at most ONE live `/run` call** — a single end-to-end confirmation once dry-run passes. Print the result, then stop. 3. **Never call the API from unit tests, examples, or a retry loop.** Assert against the sample response captured from `/dry-run` instead. 4. **On 4xx, fix the payload — do not retry.** The error body is RFC 7807 `application/problem+json` and says exactly what is wrong. 5. **On 429, honour `Retry-After`** and back off; do not tighten the loop. 6. **Read `X-MWT-Credits-Remaining`** on every response. If it drops below 50, stop making live calls and tell me. 7. If the integration needs repeated calls at runtime, **cache by input** — this tool is deterministic, so the same input always returns the same output.

Add the MiniWebtool MCP server to this project, then use the `autumnal-equinox-day` tool from it. Server URL: https://api.miniwebtool.com/v1/mcp Transport: HTTP (Streamable HTTP / JSON-RPC 2.0) Auth header: `Authorization: Bearer <MINIWEBTOOL_API_KEY>` Claude Code: ```bash claude mcp add --transport http miniwebtool https://api.miniwebtool.com/v1/mcp \ --header "Authorization: Bearer $MINIWEBTOOL_API_KEY" ``` Or add it to the MCP config file your client uses: ```json { "mcpServers": { "miniwebtool": { "type": "http", "url": "https://api.miniwebtool.com/v1/mcp", "headers": { "Authorization": "Bearer ${MINIWEBTOOL_API_KEY}" } } } } ``` Once connected, `tools/list` exposes `autumnal-equinox-day` with its JSON Schema, so you can call it directly instead of writing an HTTP client. ## Credit budget — follow these exactly This API is metered. A live call costs 1 credit; the free tier includes 1,000 credits per month. Burning them during integration is the single most common way to waste this key. 1. **Do all wiring against `/dry-run`, which costs 0 credits.** It validates the payload for real and returns a sample result with the exact response shape. Iterate there until your request builds and your parsing works. 2. **Make at most ONE live `/run` call** — a single end-to-end confirmation once dry-run passes. Print the result, then stop. 3. **Never call the API from unit tests, examples, or a retry loop.** Assert against the sample response captured from `/dry-run` instead. 4. **On 4xx, fix the payload — do not retry.** The error body is RFC 7807 `application/problem+json` and says exactly what is wrong. 5. **On 429, honour `Retry-After`** and back off; do not tighten the loop. 6. **Read `X-MWT-Credits-Remaining`** on every response. If it drops below 50, stop making live calls and tell me. 7. If the integration needs repeated calls at runtime, **cache by input** — this tool is deterministic, so the same input always returns the same output.

Every endpoint on this site is also exposed via the Model Context Protocol at https://api.miniwebtool.com/v1/mcp. Claude, Cursor, and any MCP-capable agent can discover this tool (autumnal-equinox-day) and its JSON Schema automatically — no client codegen.

# List tools the agent can call curl -s https://api.miniwebtool.com/v1/mcp \ -H 'Content-Type: application/json' \ -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' \ | jq '.result.tools[] | select(.name=="autumnal-equinox-day")'

Autumnal Equinox Day API

Endpoint

Request body

Cost & access

Response envelope

Try it

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Code examples